Heretofore a variety of fluxes, also known as mold powders or slags, have been proposed for the continuous casting of metals, particularly steel, but also copper and brass. The main functions of these fluxes are to protect the molten metal from air oxidation and to flux or solubilize and remove oxide impurities present in the melt. Additionally, lubrication of and heat transfer in the casting mold often can be enhanced by use of such flux. Typically, the flux is fed or poured on the top surface of the molten metal in the mold. Occasionally, this top surface is referred to as the meniscus.
Continuous casting of steels including aluminum- or silicon-killed steels, austenitic stainless steels, etc., is perhaps the largest user of such flux. There have been essentially two types of flux used in this connection. One is a powdery mixture of particulates, such as fly ash, silica, lime, borax, and the like. The other consists essentially of particulates of vitrified or fritted glass material ordinarily containing smeltedin halogen, especially fluorine. An example of the first type is shown in U.S. Pat. Nos. 3,642,052 and 3,788,840; of the second type, the vitrified fluxes shown in U.S. Pat. Nos. 3,649,249, 3,899,324, 3,926,246, and 3,704,744. The latter type ordinarily is the more expensive, but it is often considered necessary or desirable. The teachings of this latter group of patents are incorporated herein expressly by reference. The advantages of the instant invention will be apparent from the detailed description which follows.